BEHAVIORAL AND PHYSIOLOGICAL REACTIONS TO THREATENING STIMULI IN FEMALE COMMON MARMOSETS (CALLITHRIX JACCHUS)

Although all studies of personality examine behavior, fewer incorporate concomitant measures of neuroendocrine activity. The hypothalamic-pituitary-adrenal (HPA) axis is a key pathway modulating responses to stress in most mammals. As such, it is expected to influence individuals' responses to threatening stimuli. Here we exposed 17 captive common marmoset (Callithrix jacchus) females to a known stressor, a leather glove, to explore the relationship between urinary cortisol and personality traits. We first recorded whether individuals investigated the stimulus. We then used the proportions of time each animal spent moving about the enclosure and emitting alarm behaviors to calculate activity and agitation scores, respectively. We also explored correlations among investigation, activity, and alarm-like behavior and finally assessed HPA activity by measuring urinary cortisol across the stressor. We used linear regressions to examine relationships between behavior and physiology. Preliminary results reveal that behavior scores were poor predictors of cortisol concentrations in the urine (baseline: F7,9 = 0.48, p = 0.82; reactivity: F7,9 = 1.58, p = 0.27). We also did not detect significant correlations between behavioral categories, although activity and agitation tended to be negatively correlated (r = -0.22). These results suggest that female marmosets exhibit substantial variation in their behavioral and neuroendocrine responses to threatening stimuli. Future studies should replicate exposure-trials over time to account for this inter-individual variation in behavior and physiology.